Forklifts are used in raising, lowering or transporting cargos of heavyweight nature. Depending on the kinds of power sources employed, the forklifts may be classified into an engine-powered forklift and an electrically powered forklift, the latter of which produces little pollutant and hence is predominantly used in indoor areas.
The electrically powered forklift (hereinafter simply referred to as “forklift”) is equipped with a battery for supplying an electric current to prime movers such as a travel motor, a fluid pump motor and the like.
Referring to FIG. 1 which shows a conventional battery storage device, a battery 20 of heavyweight nature is received within a battery storage room 12 of a vehicle frame 10. The battery storage room 12 has a side opening 12a through which the battery 20 is pushed into the battery storage room 12. In case the battery storage room 12 remains opened at its top, the battery 20 may be put into the battery storage room 12 through a top opening.
When received in the battery storage room 12, the battery 20 is brought into contact with and held in place by wall portions including a side wall 12b, a front support plate 30 and a rear support plate 40. In case the battery storage room 12 has a door 12c for closing and opening the side opening 12a as illustrated in FIG. 1, one side surface of the battery 20 may be supported by the door 12c. 
Behind the rear support plate 40, there are arranged a travel motor 50 for driving rear wheels and a counterweight 52. The travel motor 50 and the counterweight 52 are fixed to the vehicle frame 10 to firmly support the battery 20. In this regard, the front support plate 30 and the rear support plate 40 are fixedly secured to the vehicle frame 10, for the purpose of which the front support plate 30 and the rear support plate 40 may be integrally formed with the vehicle frame 10 at the time of manufacturing the latter or may be welded to the vehicle frame 10.
In the meantime, the forklifts are graded according to a raising capability thereof. It may be said that the raising capability is proportional to a capacity of the battery 20 with which the forklift is equipped. The capacity of the battery 20 has something to do with a size, i.e., a length l of the battery 20 measured in a vehicle front-rear direction. In a nutshell, the electrically powered forklifts are differently graded depending on the size of the battery 20 required.
In order to assure cost-effective mass production, it is desirable that the forklifts are designed to share parts or components among similarly graded forklifts. As set forth above, however, the conventional forklift is not allowed to arbitrarily adjust the size of the battery storage room 12, meaning that, for storage of batteries differing in capacity, the length L of the battery storage room 12 measured in a vehicle front-rear direction should be changed by differently designing the vehicle frame 10. For this reason, the conventional forklift requires that the vehicle frame 10 should be differently designed on a vehicle grade basis in conformity with the size of the battery 20 required. This poses a problem in that the vehicle frame 10 cannot be shared among similarly graded forklifts, thus making it difficult to save production costs.
Furthermore, due to the fact that the battery storage room 12 is fixed in size as noted above, another problem arises in that, if a dimensional error occurs in production process or a battery standard is altered, the battery 20 cannot be received nor stably supported in the battery storage room 12.